A conventional failure tolerant engine mounting is formed by three links between the engine and its support structure. One of the links is normally unloaded, but is arranged so that in the event of failure of either of the other links it will form the third point of connection between the engine and supporting structure, thereby retaining the engine in position relative to the support structure and avoiding a potentially catastrophic failure of the engine mount.
U.S. Pat. No. 5,725,181 shows an arrangement for mounting an engine on an aircraft. A number of mounting bolts (or “pins”) are used, but in normal use at least one bolt/pin is redundant and only takes load in the event that one of the other mounting bolts/pins fails. Normally, in order to prevent vibration of the pin, it is required to tighten it up such that it clamps its respective yoke and catcher link. However, in order to inspect this pin to determine whether one of the other pins has failed, it is required to fully remove it, or at least start to extract the bolt from its lock nut. This can be a time consuming exercise, since these bolts are normally in hard to access places, and undoing the lock nut may result in the need to replace or refurbish the locking arrangement, such as replacing locking wire or coatings.